Sunshine and Clouds and Temps. Oh my!

Discussion about the FM100, FM80, and FM60 Charge Controllers

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My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Sunshine and Clouds and Temps. Oh my!

Post by raysun »

Our PV array has an STC rating of 7kW and is divided in half, each half driving an FM80 charge controller.

Here in sunny/cloudy/warm Hawaii, the typical aggregate array output is in the neighborhood of 3.6kW for 60A or so charge current feeding the battery.

Today was not a typical day. Overnight, the battery discharged to 21% SoC @ 6AM. Given there was another hour before solar charging made a dent in the discharge, the generator was fired up. (I also wanted to look into another behavior I posted elsewhere earlier.) There was a typical clear, sunny morning and for a few hours, solar charging did what it normally does. Then a blanket of clouds rolled in and it started to lightly rain. Production went below 1kW. No suprise there. However, about 12:30, the sky brightened and though there was still a uniform layer of clouds, solar production leapt to 5.8kW. On fully sunny days, 5kW is the top limit. On this cloudy day, the array skipped right past that.

The difference? Less insolation, but more important, less heat on the panels. We usually pay a 25% - 30% penalty related to PV panels' negative temperature coefficient. Today, the tariff seemed much lower.
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My RE system: 48v OB inverter and charge controller, hub and mate3s.
Location: PNW

Re: Sunshine and Clouds and Temps. Oh my!

Post by JRHill »

I was pondering if sliding ice killed our solar, snagging a wire. It has happened once before but it couldn't kill all three strings. Yup, they are tied up tight but each spring I find broken HD and UV resistant wire ties as the snow melts.

But today we are getting .2kw! Woohoo!
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